Coordinates of the segments of the hair particle
what is your level in Python? I mean are you able to reproduce code from Blender if this need?
I could share with you an approach for this, but more like workaround instead of direct solution,... because I can't understand the main purpose of your question.

What I understood, is that you want to control a particle hair system resolution, emitted trough vertices ...











Or you can only use the Sphere to control, removing  the previous script note property.



Hope this will help you!